The present invention relates to interactive graphic displays, and more particularly to touch controlled zoom and pan of graphic displays.
In conventional waveform monitoring equipment, such as oscilloscopes, spectrum analyzers, waveform monitors and the like, a waveform display is controlled by a gain and a position control in each of the x and y axes. This originally required four knobs, and the interaction between gain and offset is usually awkward. Changing the gain generally requires changing the offset, or position, to keep a certain point of the waveform on the display.
A method of touch controlled zoom of waveform displays is shown in U.S. Pat. No. 4,755,811 issued on Jul. 5, 1988. In this method a finger or other pointer device is used to touch a point on a waveform about which zoom is desired. Function buttons for moving or expanding the waveform display and for determining the axis of such movement or expansion operate in conjunction with a rotary encoder. Zooming is achieved by contacting the screen overlying a point on the waveform about which zoom is desired, and such contact and the activation of an expand button results in movement of the rotary encoder providing a gain parameter to a zoom function. Another button determines the axis along which zoom occurs. Thus zooming or panning occurs along a single axis according to the parameters defined by a couple of function buttons using only a touch pointer and a rotary encoder.
In graphics systems as shown in U.S. Pat. No. 4,532,605 issued on Jul. 30, 1985 zooming was accomplished by encompassing an area with a bounding box and then expanding the contents of the bounding box to encompass the entire screen. This produced zooming in both dimensions without using a touch screen.
What is desired is the ability to zoom or pan in either one or two dimensions without the need for function buttons, but only through using a touch screen and rotary knob.
Accordingly the present invention provides a method of touch controlled zoom and pan of graphics images using only a touch screen with defined areas and a rotary encoder knob. The touch screen has horizontal axis and vertical axis areas, optional horizontal scroll and vertical scroll areas, and a graphics display area in which the graphic information, such as a waveform, is displayed. Touching one of the defined perimeter areas determines the functionxe2x80x94pan or scrollxe2x80x94and rotating the knob performs the selected function according to the direction of rotation of the knobxe2x80x94zoom in/out or pan up/down/left/right. Alternatively the function may also be determined by xe2x80x9ctouch and holdxe2x80x9d for zoom and xe2x80x9ctouch and goxe2x80x9d for pan. Touching the graphics display area results in a two dimensional zoom or pan according to the selected function.
The objects, advantages and other novel features are apparent from the following detailed description when read in conjunction with the appended claims and attached drawing.